Add DockRegistry::frameInMDIResize()

Only emitted in a MDI layout. Emitted when one dockwidget is
being resized

src/private/DockRegistry.cpp

@@ -16,12 +16,13 @@
 #include "FloatingWindow_p.h"
 #include "LayoutWidget_p.h"
 #include "Logging_p.h"
+#include "MainWindowMDI.h"
 #include "Position_p.h"
 #include "QWidgetAdapter.h"
 #include "SideBar_p.h"
 #include "Utils_p.h"
+#include "WidgetResizeHandler_p.h"
 #include "WindowBeingDragged_p.h"
-#include "MainWindowMDI.h"
 
 #include <QPointer>
 #include <QDebug>
@@ -225,6 +226,25 @@ SideBar *DockRegistry::sideBarForDockWidget(const DockWidgetBase *dw) const
     return nullptr;
 }
 
+Frame *DockRegistry::frameInMDIResize() const
+{
+    for (auto mw : m_mainWindows) {
+        if (!mw->isMDI())
+            continue;
+
+        LayoutWidget *layout = mw->layoutWidget();
+        const QList<Frame *> frames = layout->frames();
+        for (Frame *frame : frames) {
+            if (WidgetResizeHandler *wrh = frame->resizeHandler()) {
+                if (wrh->isResizing())
+                    return frame;
+            }
+        }
+    }
+
+    return nullptr;
+}
+
 MainWindowBase::List DockRegistry::mainWindowsWithAffinity(const QStringList &affinities) const
 {
     MainWindowBase::List result;

src/private/DockRegistry_p.h

@@ -37,6 +37,8 @@ struct WindowBeingDragged;
 class DOCKS_EXPORT DockRegistry : public QObject
 {
     Q_OBJECT
+    Q_PROPERTY(
+        KDDockWidgets::Frame *frameInMDIResize READ frameInMDIResize NOTIFY frameInMDIResizeChanged)
 public:
     static DockRegistry *self();
     ~DockRegistry();
@@ -210,10 +212,16 @@ public:
     ///@brief Overload that returns the SideBar itself
     SideBar *sideBarForDockWidget(const DockWidgetBase *) const;
 
+    ///@brief Returns the Frame which is being resized in a MDI layout. nullptr if none
+    Frame *frameInMDIResize() const;
+
 Q_SIGNALS:
     /// @brief emitted when a main window or a floating window change screen
     void windowChangedScreen(QWindow *);
 
+    /// @brief emitted when the MDI frame that's being resized changed
+    void frameInMDIResizeChanged();
+
 protected:
     bool eventFilter(QObject *watched, QEvent *event) override;
 private:

src/private/Frame.cpp

@@ -792,3 +792,8 @@ int Frame::userType() const
 {
     return m_userType;
 }
+
+WidgetResizeHandler *Frame::resizeHandler() const
+{
+    return m_resizeHandler;
+}

src/private/Frame_p.h

@@ -266,6 +266,9 @@ public:
     /// @brief See DockWidgetBase::userType()
     int userType() const;
 
+    /// @brief Returns the resize handler. Used mostly in MDI mode.
+    WidgetResizeHandler *resizeHandler() const;
+
 Q_SIGNALS:
     void currentDockWidgetChanged(KDDockWidgets::DockWidgetBase *);
     void numDockWidgetsChanged();

src/private/WidgetResizeHandler.cpp

@@ -66,6 +66,11 @@ bool WidgetResizeHandler::isMDI() const
     return frame && frame->isMDI();
 }
 
+bool WidgetResizeHandler::isResizing() const
+{
+    return m_resizingInProgress;
+}
+
 int WidgetResizeHandler::widgetResizeHandlerMargin()
 {
     return 4; // pixels
@@ -127,6 +132,8 @@ bool WidgetResizeHandler::eventFilter(QObject *o, QEvent *e)
             return false;
 
         m_resizingInProgress = true;
+        if (isMDI())
+            Q_EMIT DockRegistry::self()->frameInMDIResizeChanged();
         mNewPosition = Qt5Qt6Compat::eventGlobalPos(mouseEvent);
         mCursorPos = cursorPos;
 
@@ -134,6 +141,8 @@ bool WidgetResizeHandler::eventFilter(QObject *o, QEvent *e)
     }
     case QEvent::MouseButtonRelease: {
         m_resizingInProgress = false;
+        if (isMDI())
+            Q_EMIT DockRegistry::self()->frameInMDIResizeChanged();
         updateCursor(CursorPosition_Undefined);
         auto mouseEvent = static_cast<QMouseEvent *>(e);
 

src/private/WidgetResizeHandler_p.h

@@ -119,6 +119,8 @@ public:
 
     bool isMDI() const;
 
+    bool isResizing() const;
+
     static int widgetResizeHandlerMargin();
 
     static void setupWindow(QWindow *window);